With global efforts to reduce carbon dioxide emissions stalled, the United States and five other countries are starting a new program to cut other pollutants — including methane, soot and hydrofluorocarbons — that contribute to global warming.

Secretary of State Hillary Rodham Clinton is set to announce the five-year initiative Thursday morning.

Canada, Sweden, Mexico, Ghana and Bangladesh are also participating.

The plan will be administered by the United Nations Environment Program, with a $12 million contribution from the United States for the first two years. Canada will add $3 million; contributions from the other countries are not known.

Carbon dioxide — from burning fossil fuels — plays the largest role in pushing up global temperatures, climate scientists say.

But methane, soot and hydrofluorocarbons also contribute to global warming.

Combined, those three pollutants are believed to account for 30 to 40 percent of the nearly one degree Celsius rise in global temperatures since the beginning of the 20th century.

If adopted globally, measures to reduce soot and methane emissions could slow global warming by about a half a degree Celsius by 2030, according to research published in January.